Hannity (radio) said it was a revolver! (But a revolver is a pistol).
Can't think of the last time I saw a cop with a revolver except for the older *special deputy* auxiliary types.
Most reporters use the word revolver about the same way some mystery writers do. All handguns are “revolvers”.
Of course, now that I think about it, a .357 magnum would be about as good as any in taking down a terrorist wearing questionable body armor.
Since the cop was clearly an expert, I am going to go out on a limb and say it was a .357 SIG.